1. Field of the Invention
The present invention relates to a secondary battery. More specifically, the present invention relates to a protection circuit board for a secondary battery for preventing damage to the protection circuit board from static electricity and a secondary battery using the protection circuit board.
2. Description of the Related Art
Now, portable electric/electronic apparatus, which have become more compact and lighter, such as cellular phones, notebook computers and camcorders are being actively developed and produced. Portable electric/electronic apparatus install a battery pack so as to work even in a place where no external power source is available. Considering the economic factor, the above battery pack recently adopts a chargeable/rechargeable secondary battery. Also, a secondary battery is being used in hybrid cars which need high density energy and high power. Therefore, secondary batteries are now being studied, developed and produced.
Ni—Cd batteries, Ni-MH batteries, Li batteries and Li-ion batteries are representative secondary batteries.
More particularly, a Li-ion battery has an operating voltage approximately 3 times higher than that of a Ni—Cd battery or a Ni—MH battery which is frequently used as a portable electronic apparatus power source. Also, it is widely used since it has high energy density per unit weight. The Li-ion battery usually employs a Li-based oxide as anode active material and a carbonic material as cathode active material. Generally, according to the kinds of electrolyte, secondary batteries are classified into liquid electrolyte batteries and high polymer electrolyte batteries. Batteries using a liquid electrolyte are called Li-ion batteries while those using a high polymer electrolyte are called Li-polymer batteries. Also, Li secondary batteries are being produced in various shapes. Representatively, there are cylinder-shaped, square-shaped and pouch-shaped batteries.
Considering stability, the secondary battery is used together with a protection circuit board. For the protection circuit board used in a secondary battery, a printed circuit board pattern is formed and a plurality of electric elements and a protection circuit are attached to the printed circuit board pattern. A static electricity test is performed to test the stability of the protection circuit board.
The generation of static electricity burns or melts electric elements and a protection circuit which are mounted on a protection circuit board and causes short circuits and errors in the protection circuit board.